(a) Field of the Invention
The present invention relates to a cathode-ray tube (CRT) having a faceplate panel, and more particularly, to a CRT faceplate panel for producing a uniform and clear visual image across the entire area of a viewing screen.
(b) Description of the Related Art
Generally, CRTs are designed to reproduce a picture image on a screen of a faceplate panel by exciting phosphors coated on an interior surface of the faceplate panel with electron beams emitted from an electron gun and passing through apertures of a color-selecting shadow mask. The shadow mask ensures that each electron beam lands on the correct phosphor.
The faceplate panel is usually formed with a transparent glass plate having curved interior and exterior surfaces. These curved surfaces enable the panel to withstand the high-vacuum in the CRT and facilitate the landing of the electron beams on the phosphor screen.
However, such a faceplate panel involves a relatively broad light-reflecting exterior area in peripheral portions, thereby deteriorating the brightness of those areas and distorting the appearance of the picture.
To remedy this problem, a glass plate having flat interior and exterior surfaces has been developed to be used for the CRT panel. Such a panel employs a flat tension mask to perform the color-selecting function, the flat tension mask corresponding to the flat interior surface of the panel. The flat tension mask has predetermined horizontal and vertical tensional strengths to prevent the occurrence of a doming phenomenon.
However, in this type of panel, the visual images realized through the phosphor screen and refracted on the panel appear depressed to the user in the center portion of the viewing screen. The problem becomes more severe with larger-sized screens.
To overcome this drawback, Japanese Patent Laid-Open Publication Nos. H6-44926 and 6-36710 introduce a CRT faceplate panel, which is flat on an exterior surface but curved on an interior surface. However, the images realized through these inventions appear bulged outward. Further, because the peripheral portions of the panel are considerably thicker than the center portions, the brightness of the screen is deteriorated.
In one aspect of the present invention, a cathode ray tube includes a faceplate panel having a substantially flat exterior surface and a substantially concave interior surface having a phosphor screen, a funnel sealed to a the faceplate panel, the funnel having a neck portion, an electron gun mounted in the neck portion of the funnel, a shadow mask between the faceplate panel and the electron gun, the shadow mask having an effective electron beam-passing area comprising a plurality of apertures, and a deflection yoke around an outer periphery of the funnel, wherein the panel satisfies the following condition:
1.2Rxe2x89xa6Rpxe2x89xa68R
where Rp is a curvature radius of the concave interior surface and R is 1.767xc3x97a diagonal width of an effective screen of the cathode ray tube, and the shadow mask satisfies the following condition:
0.6xe2x89xa6(Rs/Rp)xc3x97(PH/S/PH/C)xe2x89xa61.25
where Rs is a curvature radius of the shadow mask, PH/C is a horizontal pitch of the apertures formed on a central portion of the shadow mask, and PH/S is a horizontal pitch of the apertures formed on a peripheral portion of the shadow mask.
In another aspect of the present invention, a cathode ray tube includes a faceplate panel comprising a substantially flat exterior surface and a substantially concave interior surface having a phosphor screen, a funnel sealed to the faceplate panel,the funnel having a neck portion, an electron gun mounted in the neck portion of the funnel, a shadow mask between the faceplate panel and the electron gun, the shadow mask having an effective electron beam-passing area comprising a plurality of apertures, and a deflection yoke around an outer periphery of the funnel, wherein the panel satisfies the following condition:
1.2Rxe2x89xa6Rpxe2x89xa68R
where Rp is a curvature radius of the concave interior surface and R is 1.767xc3x97a diagonal width of an effective screen of the cathode ray tube; and
wherein the apertures formed on a central portion of the shadow mask are dot-shaped, and the apertures formed on a peripheral portion of the shadow mask are oval-shaped and elongated along a horizontal axis of the shadow mask, the shadow mask satisfying the following condition:
0.6xe2x89xa6(Rs/Rp)xc3x97(bs/as)xe2x89xa62.0
where xe2x80x9cbsxe2x80x9d is a horizontal radius of the apertures formed on the peripheral portion of the shadow mask, and xe2x80x9casxe2x80x9d is a vertical radius of the apertures formed on the peripheral portion of the shadow mask.
In yet another aspect of the present invention, a cathode ray tube includes a faceplate panel comprising a substantially flat exterior surface and a substantially concave interior surface having a phosphor screen, a funnel sealed to the faceplate panel, the funnel having a neck portion, an electron gun mounted in the neck portion of the funnel, a shadow mask between the faceplate panel and the electron gun, the shadow mask having an effective electron beam-passing area comprising a plurality of apertures are formed, a deflection yoke placed around an outer periphery of the funnel, wherein the panel satisfies the following condition:
1.2Rxe2x89xa6Rpxe2x89xa68R
where Rp is a curvature radius of the concave interior surface and R is 1.767xc3x97a diagonal width of an effective screen of the cathode ray tube; and
the shadow mask satisfies the following condition:
0.8xe2x89xa6(Rs/Rp)xc3x97(PH/S/PH/C)xc3x97(bs/as)xe2x89xa62.5
where Rs is a curvature radius of the shadow mask, PH/C is a horizontal pitch of the apertures formed on a central portion of the shadow mask, PH/S is a horizontal pitch of the apertures formed on a peripheral portion of the shadow mask, xe2x80x9cbsxe2x80x9d is a horizontal radius of the apertures formed on the peripheral portion of the shadow mask, and xe2x80x9casxe2x80x9d is a vertical radius of the apertures formed on the peripheral portion of the shadow mask.